Articles formed from a styrene-based polymer having a syndiotactic configuration (hereinafter referred to as SPS) have excellent heat resistance and chemical resistance but have poor impact resistance. Therefore, the polymer has heretofore been used in limited ranges. In order to improve the impact resistance of SPS articles, it has been proposed to add rubber-like elastic substances and other thermoplastic resins to SPS (see Japanese Patent Application Laid-Open Nos. 257950/1987, 146944/1989, 182344/1989, 279944/1989, and 64140/1990).
Concretely, a composition comprising SPS and, as a rubber-like elastic material, a component containing a styrenic compound (see Japanese Patent Application Laid-Open No. 146944/1989), and a composition comprising a mixture of SPS and a thermoplastic resin and/or a rubber-like polymer except SPS, and, as a miscibility-improving agent, a styrenic chain-containing, block or graft copolymer (see Japanese Patent Application Laid-Open No. 279944/1989) have been proposed.
These compositions contain, as a miscibility-improving agent, a polystyrenic chain-containing, block or graft polymer, in order to improve the miscibility of a rubber component with immiscible SPS and to improve the dispersibility of the rubber component and the interfacial strength between the constitutive components. However, the effect of the miscibility-improving agent therein is not satisfactory. Therefore, the articles formed from these compositions are not satisfactorily tough and the peeling of the surface layers from the articles could not be retarded sufficiently.